The present invention relates to the field of micro electromechanical devices such as ink jet printers. The present invention will be described herein with reference to Micro Electro Mechanical Inkjet technology. However, it will be appreciated that the invention does have broader applications to other micro electromechanical devices, e.g. micro electromechanical pumps or micro electromechanical movers.
Micro electromechanical devices are becoming increasingly popular and normally involve the creation of devices on the Am (micron) scale utilizing semiconductor fabrication techniques. For a recent review on micro-mechanical devices, reference is made to the article xe2x80x9cThe Broad Sweep of Integrated Micro Systemsxe2x80x9d by S. Tom Picraux and Paul J. McWhorter published December 1998 in IEEE Spectrum at pages 24 to 33.
One form of micro electromechanical devices in popular use are ink jet printing devices in which ink is ejected from an ink ejection nozzle chamber. Many forms of ink jet devices are known.
Many different techniques on ink jet printing and associated devices have been invented. For a survey of the field, reference is made to an article by J Moore, xe2x80x9cNon-Impact Printing: Introduction and Historical Perspectivexe2x80x9d, Output Hard Copy Devices, Editors R Dubeck and S Sherr, pages 207-220 (1988).
Recently, a new form of ink jet printing has been developed by the present applicant, which is referred to as Micro Electro Mechanical Inkjet (MEMJET) technology. In one form of the MEMJET technology, ink is ejected from an ink ejection nozzle chamber utilizing an electro mechanical actuator connected to a paddle or plunger which moves towards the ejection nozzle of the chamber for ejection of drops of ink from the ejection nozzle chamber.
The present invention concerns a method of manufacture of a thermal bend actuator for use in the MEMJET technology or other micro electromechanical devices.
In accordance with a first aspect of the present invention, there is provided a method of manufacture of a thermal bend actuator, the method comprising the steps of
(a) depositing and etching, using a first mask, a first material on a substrate to form a first conductive layer;
(b) depositing and etching, using a second mask, a second material on the substrate to form a first sacrificial layer in a manner such that at least a portion of the first conductive layer remains uncovered;
(c) depositing and etching, using a third mask, a third material on the substrate to form a first conductive bend actuator layer in a manner such that the first bend actuator layer is in electrical contact with the uncovered portion of the first conductive layer for, in use, conductive heating of the first bend actuator layer;
(d) depositing and etching, using a fourth mask, a fourth material on the substrate to form a second sacrificial layer in a manner such that the second sacrificial layer covers substantially the entire first bend actuator layer;
(e) depositing and etching using a fifth mask, a fifth material on the substrate to form a second bend actuator layer; and
(f) etching away the first and second sacrificial layers, thereby forming a first gap between the first and the second bend actuator layers and a second gap between the first actuator layer and the top surface of the underlying substrate.
In an embodiment of the invention, in step (c) the third material may be deposited and etched to form the first bend actuator layer and a first paddle layer of the bend actuator.
In such an embodiment, in step (e) the fifth material may be deposited and etched to form the second bend actuator layer and a second paddle layer of the bend actuator.
The method may comprise, before step (b), the step of:
(g) depositing and etching, using a sixth mask, a sixth material on the substrate to form a protective layer on top of the substrate in a manner such that at least the portion of the first conductive layer remains uncovered; The method can further comprise, before step (f), the steps of
(h) depositing and etching, using a seventh mask, a seventh material on the substrate to form a third sacrificial layer in a manner such that the third sacrificial layer covers substantially the entire second bend actuator layer;
(i) forming a first conformal layer of an eighth material covering the third sacrificial layer on the substrate; and wherein step (f) further comprises etching away the third sacrificial layer to form a nozzle chamber around and above the bend actuator.
The method may comprise, before step (f), the step of
(j) back etching the substrate from a back surface of the substrate to the first conductive layer for facilitating step (f).
In one embodiment, the method may comprise, before step (i), the step of:
(k) depositing and etching a ninth material on the substrate to form a ninth mask in the ninth material on top of the third sacrificial layer;
(l) etching, using the tenth mask, portions of the third sacrificial layer; and wherein step (i) further comprises depositing the eighth material in a manner such as to fill the etched portions of the third sacrificial layer to form a side wall structure of the nozzle chamber.
The method can also further comprise, before step (f) the step of:
(m) etching the first conformal layer to form a nozzle of the nozzle chamber.
Step (m) may comprise depositing and etching a tenth material to form a tenth mask on top of the first conformal layer, and etching the first conformal layer through the tenth mask to from the nozzle; and wherein step (f) further comprises etching away the tenth material.
The method may further comprise, before step (f), the step of:
(n) forming a vertical nozzle wall of the nozzle by depositing and etching an eleventh material, wherein the etch comprises an overetch.
Preferably, the first conductive bend actuator layer and the second bend actuator layer can comprise substantially the same material such as titanium nitride.
There is also disclosed a device constructed in accordance with the method.